In our joint webinar with VMware last week “Reduce Costs and Gain Control of Your Virtualized Infrastructure with Consolidated Management”, a question arose about capacity planning in a virtualized environments. I asked Rob Carruthers of Hyperformix to share his expertise on the topic. Readers of this blog may recall his podcasts on “virtualization and IT transparency” and “virtualization and capacity management”.  Rob's response follows.
-Peter

Capacity planning is becoming more important because virtualization offers a safe and logical method to get more out of IT infrastructure elements at a lower cost. For example, many companies are stacking between 10 and 15 virtual machines on a single server. Traditionally, companies have been using rules-of-thumb estimates and spreadsheets for capacity planning. Over the past few years a host of automated solutions have come on the market to assist IT professionals with getting the most out of virtualized environments. These tools fall into two broad categories – Placement tools and capacity planning tools.
 
Placement tools – Help answer the question: How do I correctly place applications within a virtual cluster for optimal performance? These tools provide analysis of current resource consumption, behavior, and assist with placing complementary workloads within a virtual cluster. Some of these tools perform linear forecasting to estimate future resource consumption based on past growth.
 
Limitations: Growth is often not linear. Demand for some applications grows faster than others, which can result in mismatches in capacity. Some clusters may have excess capacity, while others have shortages. Most placement tools do not factor in end user response time SLAs, which can result in “green” status for capacity but “red” status when users experience application slow-downs.
 
Capacity planning tools – Examine both the migration of applications to the virtual environment, and the post migration capacity requirements. These tools generally allow IT to plan growth based on the number and types of users, and take into account the non-linear aspects of business growth and can translate that into an actionable capacity plan. More mature tools also consider the end user experience and can forecast response times that users will actually experience for the business transactions they are running. Tools which provide ongoing (not just one-shot plans) are referred to as capacity management tools.
 
Limitations: These tools generally require more granular data and automated collection to produce accurate and timely results. Hypervisor and system management vendors have been adding support for key virtualized metrics of late, remediating this issue and making capacity planning easier and faster.
 
The market need for both placement tools and capacity planning tools has encouraged several vendors to create solutions. Some key players in this space include: VMware, Vizioncore, Platespin, Cirba, Neptuny, and Hyperformix.

When evaluating which method and product to use, customers should first ask several big picture questions:

• How can I get the most cost savings with virtualization without sacrificing the ability of my company to transact business?
• What tools will improve my agility when Lines-of-Business owners change the plan, or our end customers do it for us?
• Is my capacity planning tool integrated with my Hypervisor and System Management tools to provide “one source of the truth”?
• Are the answers provided by my capacity planning tool accurate and reliable?

The full potential of virtualization depends on delivering financial returns back to the business. Capacity planning can ensure economic returns can be delivered safely without negatively impacting performance.

Rob Carruthers 
Director of Product Marketing 
Hyperformix